(b) The second, and overriding. Reason relates to the way in which sugar factory evaporators are designed and operatic. conventional design practice is to manufacture all tail vessels in the same set with equal heating surface, and this applies in most cases for our data. Thus for the different effects of each set, a in the above equation is constant. Likewise, without vapour bleed the heat transfer rate Q is substantially equal for each effect. Thus HTC must be approximately inversely proportional to t . since the set must balance itself out, the conditions which give rise to low HTC-high brix and low temperature in the last effect – inevitably also result in high t . it is therefore HTC which governs t in this situation, at least to an extent which overwhelms any influence in the reverse direction which t may have on HTC independently on these constraints.